Have to agree with the hawk for the coolness factor. They watch TV and follow you around the room. If your coral banded is large, it will probably be OK.
A gold head sleep goby is pretty cool to watch too... Mine is always working, either cleaning the sand or moving things around. You must have sand for him.... In my avatar pic, you can see my GHSG. He looks like he smoking a cigar, but that day he was re-arranging pieces of codium around in the tank. Even the neighbor hood kids stop over all the time specifically to watch him blowing sand from his gills. They love him.
Although, a GHSG is one fish I would not buy sight unseen. I have seen lots of them with belmishes, or messed up colors. You have to watch for a pretty one and snatch him up.